Benjemin Bale

I WASWONDERING IF IT IS OK TO RUN LEADED RACE GAS IN OUR CARS, I KNOW SOME ARE RUNNING RACE FUEL BUT I WOULD LIKE TO KNOW IF IT IS LEADED OR UNLEADED. THANKS TO ALL

turbobrat930

take your caps lock OFF.... and if you not running an o2 sensor, then yes, you can run leaded race fuel. But what mods have you done to your car in order to take advantage of the race fuel??

Benjemin Bale

Sorry about the caps lock, the car has the following mods - sc cams , k27 , twin plugged w electromotive ign , schnell headers , euro fuel head , 1 bar spring. The car runs fine on premium but I just wanted to throw about 5 gallons of the good stuff in just to try it out. The 02 sensor is still hooked up but I will be cutting the gas with premium unleaded. I used to do this with my Grand National with good results. I may be just wasting my money but its worth a shot.

nathanUK '81 930 G50

The idea of race gas it to remove detonation. If you have already had some then it is way too late. If you haven't got any then there will be no benefit from the race gas.

Gary R.

I would stick with 100 octane unleaded at the track....

onboost

Nathan,

I'd have to disagree with you here..even with the mods etc.. the car will still respond to the higher octane/leaded fuel just by the nature of what it is...

I put 100 octane in one of my cars a couple of weekeds ago and I could tell a noticable difference... and no , I do not have any detonation issues.

Just my 02 cents..

930targa

i have heard from some people that it makes the engine run cooler , while i would not really like to think its true , it may actually happen to an air cooled engine, not sure ....

also another thing is if you have a boost controller of some sorts and maybe a wideband a/f guage you may be able to squeeze a little more power out the car safely by raising boost while on the race gas .

iv'e actually seen CIS p-car setups run like absolutely crap under boost on anything other than race gas, not detonating just sluggish and running absolutely bad, sunoco 112 fixed it. also it is advised not to run more than 20psi on pump gas, im not sure why its just what some reliable sources have told me .

AND if you don't want to be paying the 6-7 dollar per gal. the race gas is everytime you go to the track, a good alternative is to buy a methanol injection kit ....

and also i have put 110LL airplane fuel in my car (not in the porsche yet ) and i had an O2 sensor hooked up without any issues , i know its bad to run leaded gas with cats but i think the o2 sensors will be alright

Benjemin Bale

Thanks for the input so far , I think I will go ahead and try it out just to see how the car responds to the better fuel. The car has had no previous detionation and ran fine with regular premium but I just wanted to try a little race gas just to see if there was any difference. Thanks again

JFairman

Unless race gas puts out higher BTU's of heat and energy I don't see how it will give you more power or make the engine run better, but maybe it does.

If you're getting better running and more power with race gas it means the street gas you're using is not high enough octane for your compression ratio or your head temperatures are overheating and you are having detonation that you may not be able to hear over all the other noise.
Detonation will over heat the heads and break piston rings from the explosive pounding or just wear out the ring lands. It can also create pitting on piston crowns and eventually burn a hole in them.

Higher octane slows down combustion.
Higher octane/quality street gas often has more detergents in it that will leave less carbon deposits on the backsides of intake valves and combustion chambers.
With the right octane the sparkplug is the only thing triggering combustion and instead of the mixture exploding all at once there will be a flame front that travels across the combustion chamber like a fast efficiant fooomph instead of exploding all at once, in a single offset sparkplug set up in a hemi head.
Dual plugging shortens the flame travel by lighting it off from opposite ends of the combustion chamber simultaneously, allowing you to retard the timing a little which allows a little bit higher compression for more heat and power, or volumetric efficiancy.

4 valve heads with a centrally located spark plug also allow higher compression ratios because your lighting off the mixture from the center and the flame front travels a shorter distance outwards 360 degrees equally insteads of from one side of the chamber like a stock 911.

Running leaded gas will eventually leave a coating on the O2 sensor ruining it.
Sometimes they can be cleaned with a propane torch.
The lead is slightly helpful as a valve seat lubricant and top cylinder lubricant though.

hth..

nathanUK '81 930 G50

I watched some tests they did on TV with slightly more modern cars and even they did not give more power with higher octane.

As for raising boost, the diaphragms in the WUR's we have do not like more than 1bar. Same for the stock head studs.

911rudy

From what I have learned over the years is that octane and compression ratio are completely intertwined. If you put in a high octane fuel but don't have the compression to go with it you are wasting your money. All high octane fuel is, is a fuel that will not explode or burn at a lower compression ratio. It is used to prevent detonation and really has no other affect on performance. I am sure that there are some instances that there can be some unexpected improvement that is a combination of timing, compression and AFR. Most newer cars will state in their manuals that higher octane fuel will not improve performance. And if they are computer controlled, which most are, it can actually hurt performance.

A930Rocket

The only reason I use 100 octane is to prevent detonation at the track when I'm on the boost for extended periods of time. I used 114 leaded and 93 unleaded as a mixture to cut down the cost of straight 100 octane, but it fouled out the O2 sensor for my A/F quickly.